This investigation is designed to increase understanding of the mechanics and function of human synovial joints. The detection of the contact area patterns in synovial joints provides information concerning the mechanisms by which joints accomodate the forces imposed by activity. This information adds to the body of knowledge related to the physiology and pathophysiology of the skeletal system. This investigation will provide for systematic comparison of contact areas, force-to-contact area ratios and sites of pathologic change for the ankle and phalangeal joints of the hand. It should provide additional insight into the interesting question of why certain joints are relatively resistant to degenerative joint disease in the absence of predisposing trauma. The information derived from these studies on the magnitude of the articular contact surfaces and the mechanisms of load transmission across the surfaces of normal joints will provide baseline design parameters for a more logical "evolutionary" design process for future implant systems.